Image processing is a fairly well developed science of modifying and analyzing pictures, graphics designs, and the like. See e.g., Introduction to Image Processing Algorithms, Benjamin M. Dawson, Byte Magazine, March 1987, pp. 169–186. A variety of different approaches to image interpolation have been proposed and used. Known manner colorimetry constructs and methods of multidimensional color space data interpolation are described in the literature, such as Principles of Color Technology, by Billmeyer and Saltzman, John Wiley & Sons, Inc., NY, publishers, copr. 1981 (2d ed.); Color Science: Concepts and Methods, Quantitative Data and Formula, by Wyszecki and Stiles, John Wiley & Sons, Inc., NY, publishers, copr. 1982 (2d ed.); and Fundamentals of Interactive Computer Graphics, Foley and Van Dam, Addison-Wesley Publishing Company.
Basically, colorimetry has long been recognized as a complex science. Essentially, as defined in 1931 by the Commission Internationale L'Eclairage (CIE), three primary colors (X, Y, Z) can be combined to define all light sensations we experience with our eyes; that is, the color matching properties of an ideal trichromatic observer defined by specifying three independent functions of wavelength that are identified with the ideal observer's color matching functions form an international standard for specifying color. In general, it has been found possible and convenient to represent color stimuli vectors by a three-dimensional spatial construct, called a tristimulus space or a colorspace. The fundamentals of such three-dimensional constructs are discussed in Billmeyer and Saltzman, supra, and the above cited Color Science: Concepts and Methods, Quantitative Data and Formulae, by Wyszecki and Stiles, published by John Wiley & Sons, Inc., copyright 1982 (2d ed.), see e.g. at pages 119–130. One of the most commonly referred to systems is the Munsell color system, a system for designating colors, which employs three perceptually uniform scales:
Munsell hue—the dimension that determines whether a color is blue, green, yellow, red, purple, or the like, without regard to its lightness or saturation;
Munsell value—the dimension that indicates the apparent luminous transmittance or reflectance of the object on a scale having approximately equal perceptual steps under the usual conditions of observation; and
Munsell chroma—the dimension that corresponds most closely to saturation, which is the degree of vividness of a hue.
A variety of trichromatic model systems provide alternatives for both the hardware and software system designers—e.g., the red, green, blue (RGB) model commonly used in computer video displays; the cyan, magenta, yellow (and black) (CMY(K)) model used extensively in color hard copy apparatus; the hue, saturation, value (HSV) model; the hue, lightness, saturation (HLS) model; the luminance, red-yellow scale, green-blue scale (L*a*b*) model; the YIQ model used in commercial color television broadcasting; and others. Color input and output devices—such a scanners, cathode ray tube (CRT) video monitors, and printers—present color images in a device-dependent fashion. For example, CRT guns are driven by RGB values (voltage levels or other input signal functions, referred to hereinafter as data triplets or color coordinates) that are stored in a frame buffer. Those RGB values index over the color space of each particular model video monitor; in other words, the color produced by a CRT on a pixel of its screen for a given RGB triplet of values is unique to that device. Because of device design dependency, the same RGB triplet may produce a very different color or hue when displayed on a different model CRT and still a different color in a hard copy made with a color printer.
Color transformation (also referred to in the art as color correction and cross-rendering) between model systems in digital data processing presents many problems to the original equipment manufacturer. The transformation of data from one device to another device is difficult because the color matching relationship between those systems are generally non-linear. Therefore, a crucial problem is the maintaining of color integrity between an original image from an input device (such as a color scanner, CRT monitor, digital camera, computer software/firmware generation, and the like) and a translated copy at an output device (such as a CRT monitor, color laser printer, color ink-jet printer, and the like). A transformation from one color space to another requires complex, non-linear computations in multiple dimensions. Since such is not describable mathematically, it is known to use very large look-up tables to approximate a transformation between trichromatic model systems to correlate the wide spectrum of color hues that exist.
Another major problem is that a given code—namely, a set of tristimulus space coordinates—for a particular chroma, e.g., “Light Blue No. 1,” can produce visual perceptual differences that are dependent on the current printer—and may vary from replaceable print cartridge to print cartridge—and on the current print media being used. Moreover, the end user may have a variety of printers and media at their disposal for a current print job.
The use of printed test patterns and optical hardware analysis of such patterns for various purposes including color matching are known in the art. Color correction algorithms can be used to match color with respect to standards. See e.g., U.S. Pat. No. 5,732,151, Mar. 24, 1999, by Moon et al. for a COMPUTERIZED MEMORY MAPPING METHOD FOR TRANSFORMING COLOR DATA (assigned to the common assignee herein). Often however, there is simply no substitution for the use of human visual acuity to render a final decision as to a “best” hard copy rendition.
When an end user has the capability of selecting from a plurality of color hard copy apparatus or a plurality of print media, there is a need for simple useful tools for providing an end user with representative examples of the results of each without the need for time-consuming experimental printing and without wasting valuable consumable resources.